Cleavage. 100%. Any flash of any cleavage at any time gets my attention
After that, it's watching woman in various situations and trying to work out their bra size

Catching my eye
 

For me, well anything! Depending on her position relative to me. I love seeing her ass in tight pants, her long legs, her slight peek of cleavage as she leans forward, a bare belly, the way her pants hug her pussy, the nape of her neck, her smile, her eyes...
Yeah, I absolutely cannot say any one thing. I like the whole package, no matter what part is right in front of me!
Any woman who is wearing tight fitting clothing that shows off ANY part of her makes me quiver with excitement. Young, old, slim, heavy, tall or short. I want them all! Tee hee hee...

Mad magazine's mascot, Alfred E Newman said one time “the first thing you notice about a woman, depends on which way she's walking ”. Truer words were never spoken for me.

I love seeing back muscles. Not overly muscular, but just a bit of tone. Showing off the back is really sexy to me, and to see some definition is hot. I think it has something to do with TV I saw growing up, where all you could ever see in sex scenes was a naked woman's back.

Woman's body, mind of a child
 

My husband says:
She was pretty til she spoke

Yep, we had one of those in the neighborhood. Single mom, smoking hot, didn't talk much. Then one day her true colors came out. No matter lovely her physical appearance, it was all wiped away in an instant.

It's always the ass and legs for me. It's mesmerizing to me... like it's all I want to stare at on a fine woman. In fact, 99% of the pics and vids I save from the net are exactly that. It could be something as simple as a woman wearing only a thong shown walking, from a low angle, of course.

There was 1 girl I was so smitten with back in college, and her legs and ass were out of this world; they were shapely with some muscle since she ran track and was a pompom girl for a while years prior... sadly I was destined to only be in the classic "friend zone" with her (:(), but damn I could not stop staring at her perfect legs and ass... I still get hard just remembering. She knew how I felt but I doubt she knew the extent of just how much I fantasized about her and those incredible legs/ass she had..... goddamn she was somethin' else. I remember one day hanging out with her in the dorm lobby and she had denim cut-off style shorts on....oh my god that visual...

Living in Japan it’s teeth!
There are pretty women everywhere, but mangled smiles are more common than they should be.

Otherwise it would have to be breasts. The wife reckons I do it without even realising. I told her that’s called being a man. We can’t help it. Biology is hard to deprogram!

For me it is two things:

1. Tits, I especially love to see a woman with big tits going braless. But any sized female with pokey nipples is just fine.

1a. If wearing a bra, I love to see cleavage. Two big ones pushed up together makes for a mighty fine view.

I’m exactly the same. Whenever I see a women in public, the first I try to see if she wearing a bra. It’s like instinct. And I see she’s not, it immediately gets my attention.